Questions answers and facts relating to the human brain

Approximately 20% of the blood flowing from the heart is pumped to the brain. The brain needs constant blood flow in order to keep up with the heavy metabolic demands of the neurons.

What is the largest part of the brain?

The biggest part of the brain is the cerebrum which makes up 85% of the brain’s weight. The cerebrum is the thinking part of the brain and it controls your voluntary muscles.

Does the brain work at the Speed of Light?

No, far from it. Axons, the long output connection from a cell, come in two types: myelinated and unmyelinated. Myelinated axons have an extra layer of “insulation,” a fatty substance, which allows the impulse to travel about 10 to 100 meters per second. Unmyelinated axons only transmit at about 1 meter per second. When the signal reaches the end, it has to cross the synapse to influence the next cell, which adds about 5 ms. 10 meters per second = 22.356 mph and 100 meters per second = 223.561 mph. As you can see it is a lot slower than the speed of light in a vacuum which is exactly 299,792,458 metres per second, or 186 000 miles per second, or 670,616,629 mph.

What are studies of the brain called?

The study of the brain and its functions is known as neuroscience.

Psychology is the scientific study of the mind and behavior.

Neurophysiology is the study of normal healthy brain activity.

Neurology and psychiatry are both medical approaches to the study of the mind and its disorders and pathology or mental illness respectively.

How many main parts to the brain are there?

The human brain can be divided into three main parts: the forebrain, midbrain, and hindbrain:

1/ The forebrain includes the several lobes of the cerebral cortex that control higher functions.

2/ Midbrain functions include routing, selecting, mapping, and cataloguing information, including information perceived from the environment and information that is remembered and processed throughout the cerebral cortex.

3/ Hindbrain – (rhombencephalon) is a developmental categorization of portions of the central nervous system in vertebrates. A rare disease of the rhombencephalon, “rhombencephalosynapsis” is characterized by a missing vermis resulting in a fused cerebellum. Patients generally present with cerebellar ataxia.

What is a neuron?

A neuron is a nerve cell in the brain. The human brain is made up of approximately 100 billion (100,000,000,000) neurons.

Do men have a larger brain than women?

Male humans have about a 10% larger brain than females. A study of 46 adults aged 22-49 years found an average brain volume of 1273.6cc for men, ranging from 1052.9 to 1498.5cc, and 1131.1cc for women, ranging from 974.9 to 1398.1cc. However differences in male and female brain weight and size do not mean differences in mental ability. There is evidence of a gradual increase in average brain size over the last centuries, estimated to have been around 0.5% per decade.

Is a computer smarter than a human brain?

The brain has a processing capacity of 0.1 quadrillion instructions per second. The fastest super computer in the world, called Roadrunner is capable of handling 1.026 quadrillion calculations per second. However the computational power of the human brain is difficult to ascertain, as the human brain is not easily paralleled to the binary number processing of computers. For while the human brain is calculating a math problem, it is subconsciously processing data from millions of nerve cells that handle the visual input of the paper and surrounding area, the aural input from both ears, and the sensory input of millions of cells throughout the body. The brain is also regulating the heartbeat, monitoring oxygen levels, hunger and thirst requirements, breathing patterns and hundreds of other essential factors throughout the body. It is simultaneously comparing data from the eyes and the sensory cells in the arms and hands to keep track of the position of the pen and paper as the calculation is being performed.

Can an adult grow more brain cells?

A landmark study in late 1998 by researchers from Sweden and the Salk Institute in La Jolla, California, showed for the first time that some brain cells in mature humans may regenerate under certain circumstances.

Do humans only use 10% of the brain?

No, we use all of our brain.

Does alcohol kill brain cells every time you drink?

The idea that alcohol kills brain cells has long been promoted. Drinking alcohol does not actually “kill” brain cells. Roberta Pentney, professor of anatomy and cell biology at the University at Buffalo, concludes that alcohol does not kill brain cells but it damages the dendrites, the branched ends of nerve cells that bring messages into the brain cell causing damage to the way the cells in the brain communicate. Luckily the damage is largely reversible and not permanent. However years of alcohol abuse can cause serious neurological damage, including Wernicke-Korsakoff syndrome.

In what part of the brain do you get brain tumors?

Brain tumorsare classified depending on the exact site of the tumor, the type of tissue involved, benign or malignant tendencies of the tumor, and other factors. Primary (true) brain tumors are commonly located in the posterior cranial fossa in children and in the anterior two-thirds of the cerebral hemispheres in adults, although they can affect any part of the brain.

How are memories stored and retrieved?

Unfortunately we don’t yet comprehend exactly how this happens or how memories are recalled years later for retrieval.

How and why do we dream?

Dreams have fascinated nearly everyone for thousands of years. There are two different schools of thought as to why we dream: the physiological school, and the psychological school. While many theories have been proposed, not single consensus has emerged as to why we dream. Some researchers suggest that dreams serve no real purpose, while other believe that dreaming is essential to mental, emotional and physical well-being. One theory for dreaming suggests dreams serve to clean up clutter from the mind.

Are humans born with all their brain cells?

Babies are born with around a 100 billion brain cells, but only a small number of neurons are actually connected. By three years of age a childs brain has formed about 1,000 trillion connections, about twice as many as adults have. At around 11 years, the brain begins to prune unused connections. Connections that are used repeatedly in the early years become permanent; those that are not are eliminated. Hence the saying, “use it or lose it.”

How and why do we sleep?

We still don’t fully understand the importance of sleep however we do know that sleep is the time when the body does most of its repair work; muscle tissue is rebuilt and restored and tissure building growth hormone is secreted during sleep. A good way to understand the role of sleep is to look at what happens when we don’t get enough sleep.

Are IQ tests accurate measures of intelligence?

First you need to define intelligence, a very hard task, think about it. Intelligence is an encompassing term. “We cannot measure intelligence when we have not defined it” said journalist Walter Lippmann in the early 1920′s. According to most current definitions intelligence is made up of the skills of logical reasoning, problem solving, critical thinking, and adaptation.

IQ tests are not very reliable and the scores may vary as much as 15 points from one test to another. The average IQ scores for many populations have been rising at an average rate of three points per decade since the early 20th century with most of the increase in the lower half of the IQ range.

When is the brain considered dead?

Brain death is the irreversible end of all brain activity (including involuntary activity necessary to sustain life) due to total necrosis of the cerebral neurons following loss of blood flow and oxygenation. A brain-dead individual has no clinical evidence of brain function upon physical examination. This includes no response to pain and no cranial nerve reflexes. Reflexes include pupillary response (fixed pupils), oculocephalic reflex, corneal reflex, no response to the caloric reflex test and no spontaneous respirations. The diagnosis of brain death needs to be rigorous to determine whether the condition is irreversible. Legal criteria vary, but it generally requires neurological exams by two independent physicians. The exams must show complete absence of brain function, and may include two isoelectric (flat-line) EEGs 24 hours apart.

If tests show brain activity, the patient may be in a coma or vegetative state. A brain dead person doesn’t show brain activity. It is important to distinguish between brain death and states that may mimic brain death. Some comatose patients can recover, and some patients with severe irreversible neurologic dysfunction will nonetheless retain some lower brain functions such as spontaneous respiration, despite the losses of both cortex and brainstem functionality. Thus, anencephaly, in which there is no higher brain present, is generally not considered brain death, though it is certainly an irreversible condition in which it may be appropriate to withdraw life support.

Today, both the legal and medical communities use “brain death” as a legal definition of death. Using brain-death criteria, the medical community can declare a person legally dead even if life support equipment keeps the body’s metabolic processes working.